The present invention relates to-vibratory pavement breakers and particularly to an electrohydraulic vibratory pavement breaking system with pneumatic or hydraulic springs, providing, with the vibratory mass of the breaker, a system tuned to a resonant frequency especially suitable for pavement breaking.
Vibratory pavement breakers which have heretofore been proposed utilize a vibratory beam which is flexed, much like a violin string, by a rotatably driven eccentric weight at one end of the beam. The opposite end of the beam is arranged to impact the pavement to be broken. The beams of such pavement breakers are supported on shafts by bearings and are subject to forces which tend to rupture or otherwise destroy the bearing material and the shafts. The reliability of such vibratory beam breakers is therefore less than desirable. Such vibratory beam devices are shown for example in U.S. Pat. No. 4,515,408 issued May 7, 1985 to R. A. Gurries.
Hydraulic oscillators have also been used in percussive tools for earth boring and pile driving. There a hammer and anvil system is utilized. Such percussive tools are described, for example, in U.S. Pat. Nos. 3,386,339 issued Jun. 4, 1968 to R. L. Selsam, U.S. Pat. No. 3,371,726 issued Mar. 5, 1968 to J. V. Bouyoucos, U.S. Pat. No. 3,382,932 issued May 14, 1968 to B. A. Wise, U.S. Pat. No. RE 30109, issued Oct. 9, 1979 to J. V. Bouyoucos, et al., U.S. Pat. No. 3,903,972, issued Sep. 9, 1975 to J. V. Bouyoucos, et al. and U.S. Pat. No. 3,911,789 issued Oct. 14, 1975 to J. V. Bouyoucos. The hydraulic oscillator is a free running device which embodies an oscillating valve-hammer which impacts an anvil at one end of the cycle of hammer oscillation. A free running hydraulic oscillator is not desirable for pavement breaking. For pavement breaking, control of the vibratory frequency as well as the vibratory displacement is required in order to consistently break the concrete into rubble size particles. Such rubble has been found desirable so as to provide a bed which is compacted and upon which an asphalt surface may be laid.
It is the principal object of the invention to provide a system reliably operative for breaking and rubblizing highway pavement.
It is another object of the present invention to provide an improved vibratory pavement breaker which is electrohydraulically. driven and controlled and which utilizes a mass resonant with a spring system, the springs being either hydraulic or pneumatic and the mass being driven electrohydraulically via a control system, which may be a feedback control system, for maintaining the vibration at the resonant frequency with the amplitude and position thereof in impacting relationship with the pavement to be rubblized.
It is the further object of the invention to provide an improved electrohydraulic pavement breaker system with a plurality of pavement breakers arranged in an array on a vehicle so that the array is advanced along the pavement to be broken and rubblized to break a swath of pavement equal in size to the width of the breakers across the swath.
It is a still further object of the present invention to provide an improved pavement breaker having a mass which is reciprocally driven toward and away from the pavement and which provides the vibratory forces against the pavement via a pivoted link which can drag along the pavement and isolates the driver including its mass from the pavement thereby reducing excessive sidewise forces on the surfaces (bearing surfaces) over which the mass moves as it is vibrated.
It should be understood that one or more of the forgoing objects, and not necessarily all thereof, may be achieved in accordance with the invention.